Method for preparing and purifying 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol

ABSTRACT

A process is disclosed for the preparation and purification of 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol. Accordingly, isopropenylphenol, its dimers or oligomers undergo isomerization in the presence of an acid catalyst, the reaction mixture is optionally neutralized by adding a base and 3-(4-hydroxyphenyly)-1,1,3-trimethylindan-5-ol is isolated from the reaction mixture by fractional distillation.

The present invention relates to a process for the preparation and purification of 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol by isomerisation of isopropenylphenol, its dimers or oligomers and subsequent distillation of the reaction mixture.

Various processes for preparing 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol, referred to below as bisphenol indane, are already known.

Thus U.S. Pat. No. 2,754,285 and U.S. Pat. No. 2,819,249 disclose a preparative route to indanes via the acid-catalysed dimerisation of α-methylstyrene. The indanes are subsequently sulphonated and then saponified with potassium hydroxide.

U.S. Pat. No. 2,979,534 discloses that the monomeric isopropenylphenols obtained by decomposition of bisphenols can be dimerised in the presence of aromatic sulphonic acids or mineral acids at temperatures of 110 to 160° C. to form bisphenol indane. The decomposition of bisphenol and formation of indane may also be carried out in one step. A product of low purity, which even after recrystallisation from benzene/cyclohexane had a melting point of only 165-166° C., was obtained by this process.

U.S. Pat. No. 3,264,357 discloses the preparation of bisphenols by the reaction of a mixture of two isomeric forms of the dimeric isopropenylphenol with phenols in the presence of strong acids. It is reported that, in the absence of reactive phenols, bisphenol indane is formed at a reaction temperature of 90° C. According to U.S. Pat. No. 3,264,358, bisphenol indane can be obtained by the reaction of a mixture of the two isomeric forms of the dimeric isopropenylphenol with strongly acid catalysts, for example, by tempering for two hours in boiling concentrated hydrochloric acid.

U.S. Pat. No. 3,288,864 discloses the preparation of bisphenol indane by self-condensation of monomeric isopropenylphenol in the presence of Friedel-Crafts catalysts at temperatures of from 50 to 150° C. and JP-A 60/35150 discloses the isomerisation of isopropenylphenol or of its oligomers in the presence of solid catalysts such as aluminium oxide or terra alba.

According to U.S. Pat. No. 4,334,106, bisphenol indane can be prepared by the reaction of isopropenylphenol or its oligomers in halogenated carboxylic acids or formic acid at temperatures of from 0 to 90° C.

According to JP-A 5/294879, bisphenol indane can be obtained by thermal decomposition of bisphenol A in the presence of activated clay and U.S. Pat. No. 3,271,463 discloses the formation of bisphenol indane as a by-product during the treatment of bisphenol A with aqueous sulphuric acid at 90 to 150° C. During both processes relatively large quantities of spirobisindane bisphenol are formed and this has to be separated from aromatic hydrocarbons by recrystallisation.

The processes described are in many cases still unsatisfactory for an industrial production of bisphenol indane for use as starting material for the production of plastics. In order to obtain bisphenol indane in the purity required for this purpose, it is necessary in an expensive process to separate the reaction product from the reaction mixture and to purify it by recrystallisation. A process which makes it possible to dispense with these steps has now been found.

This invention provides a process for the preparation and purification of bisphenol indane, wherein isopropenylphenol, its dimers or oligomers are isomerised in the presence of an acid catalyst, the reaction mixture is optionally neutralised by the addition of a base and bisphenol indane is subsequently isolated from the reaction mixture by distillation (e.g. fractional distillation).

Isopropenylphenol, its dimers or oligomers or mixtures thereof are used as starting materials for the process according to the invention. These are easily accessible and can be prepared, for example, by the methods described in U.S. Pat. No. 3,288,864 or U.S. Pat. No. 4,201,877.

The isomerisation is preferably carried out in the presence of a solvent. A large number of different solvents are suitable for use as the solvent. Examples are hydrocarbons such as petroleum ether, cyclohexane, benzene, toluene or xylene, alcohols such as methanol, n-propanol or n-butanol, carboxylic acids such as formic acid or acetic acid, propionic acid, halogenated carboxylic acids such as trichloroacetic acid or trifluoroacetic acid, chlorinated hydrocarbons such as methylene chloride, chloroform, trichloroethylene or carbon tetrachloride, substituted aromatics such as chlorobenzene or nitrobenzene; dimethyl sulphoxide, dimethylformamide, dimethylacetamide or N-methylpyrrolidone are also suitable. Preferably chlorobenzene is used. The quantity of solvent is preferably two to three times the quantity of isopropenylphenol used.

The isomerisation reaction is carried out in the presence of an acid catalyst. Bronsted acids or Lewis acids may be used as catalysts for the process according to the invention. Examples are mineral acids such as hydrochloric acid or sulphuric acid, organic acids such as sulphonic acids or halogenated carboxylic acids, boron trifluoride and metal halides such as AlCl₃, FeCl₃ or ZnCl₂. Besides these heterogeneous catalyst systems may also be used, for example, in the form of a fixed bed. Examples are acidic ion-exchange resins, zeolites, oxides or hydroxides or mixed oxides of transition metals or of rare earths, heteropolyacids, Al₂O₃, SiO₂ and mixtures thereof Preferably Lewis acids and particularly preferably boron trifluoride are used as catalysts. In a preferred embodiment of the process the catalyst is added, optionally in portions, in a quantity of from 0.002 to 5 wt. %, preferably from 0.3 to 0.5 wt. %, based on the quantity of isopropenylphenol used, to the reaction mixture after heating to a temperature within the range of 60 to 110° C., preferably 70 to 90° C.

The isomerisation is carried out preferably at a temperature within the range of 0 to 160° C., particularly preferably at a temperature within the range of 110 to 150° C. and most preferably at 130 to 140° C. The reaction is allowed to take place for 1 to 600 minutes, particularly preferably for 2 to 60 minutes.

Subsequent to the isomerisation reaction, the reaction mixture is optionally neutralised by the addition of a base. The neutralisation is carried out preferably at a temperature within the range of 60 to 100° C., particularly preferably at 70 to 90° C. A large number of different bases or their mixtures are suitable for the neutralisation. Examples are metal hydroxides such as NaOH, KOH, Mg(OH)₂, Ca(OH)₂, alcoholates such as sodium methylate, sodium ethylate, sodium phenylate, potassium methylate, potassium ethylate, potassium phenylate, magnesium methylate, magnesium ethylate, magnesium phenylate, calcium methylate, calcium ethylate, calcium phenylate, aluminium isopropylate, carboxylates such as sodium formate, sodium acetate, sodium benzoate, calcium formate, calcium acetate, carbonates such as sodium carbonate, potassium carbonate, calcium carbonate, magnesium carbonate, (NH₄)₂CO₃, hydrogen carbonates such as NaHCO₃, KHCO₃ or NH₄HCO₃, mixtures of NH₄HCO₃ and ammoniun carbonate, ammonia, amines such as triethylamine, diethylamine, ethylamine, trimethylamine, dimethylamine, methylamine and their solutions in water or in organic solvents which are immiscible with the reaction medium. Preferably aqueous sodium hydroxide solution is used as base. If a base which forms a two-phase system with the reaction mixture is used, the organic phase containing the bisphenol indane is separated off after the neutralisation.

Bisphenol indane is then isolated by fractional crystallisation from the neutralised reaction mixture or from the organic phase containing the bisphenol indane. Although U.S. Pat. No. 4,366,328 instructs that bisphenol indanes already undergo decomposition at temperatures from 150° C. with the formation of the corresponding indenes, with acceleration of the decomposition reaction under reduced pressure, bisphenol indane of high purity is successfully obtained in good yield from the reaction mixture by distillation. Here first of all low-boiling components (for example, solvent and unreacted educt) are removed, then bisphenol indane is distilled off. This is carried out preferably at pressures within the range of 10⁻³ to 10¹ mbar and at temperatures of from 160 to 230° C., particularly preferably at 10⁻² to 10⁰ mbar and 175 to 205° C. The separation of the low-boiling components and the distillation of the bisphenol may be carried out in a single step or in succession. Alternatively, the separation may be carried out for example in two distillation columns arranged in tandem, with the high-boiling components being obtained at the foot of the first column and the low-boiling components as the overhead product of the second column, while bisphenol indane is removed at the foot of the second column. The distillation is carried out preferably under an atmosphere of inert gas, for example, nitrogen or argon. It is useful to free the reaction mixture from atmospheric oxygen before the distillation by passing in inert gas.

Owing to its high purity, the bisphenol indane prepared by the process according to the invention is eminently suitable as a starting material for the production of high-grade plastics, for example, polycarbonates.

EXAMPLE

800 g dimeric isopropenylphenol was dissolved in 2000 ml chlorobenzene. The reaction mixture was heated to 80° C. and then 2.8 ml BF₃ etherate was added. The reaction solution was heated to boiling and then maintained under reflux for 40 minutes at 132° C. The catalyst in the reaction solution was then neutralised at 80° C. by the addition of sodium hydroxide solution (1.164 g NaOH to 300 ml water). The aqueous phase was separated off and the organic phase was removed for distillation. At a pressure of 1 mbar, solvent and unreacted educt were first of all distilled off. Finally, at an overhead temperature of 198° C., 440 g (corresponding to 55% of the initially weighed quantity of isopropenylphenol) of a fraction having a bisphenol indane content of 92% was isolated. 

What is claimed is:
 1. A process for preparing purified 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol comprising (a) isomerizing at least one member selected from the group consisting of isopropenylphenol, a dimer of isopropenylphenol and an oligomer of isopropenylphenol in a reaction mixture and in the presence of an acid catalyst, and (b) neutralizing said reaction mixture by adding a base, and (c) isolating 3-(4-hydroxyphenyl)-1,1,3-trimethylindan-5-ol from the neutralized reaction mixture obtained in (b) by fractional distillation. 